Safety device for gas apparatus

ABSTRACT

A safety device for gas apparatus has a pilot flame at the base of a tube with a thermocouple close beside the flame. Spaced above the flame is a metal grill not reached by the flame when it burns in an atmosphere of normal composition. When the air has a high CO2 content the flame is displaced from the pilot nozzle and is lifted to the grill. The thermocouple therefore cools and actuates the closure of the gas supply to the apparatus. A gridded aperture in the base allows air to flow in past the thermocouple thereby aiding its cooling. A gridded aperture at the top of the tube allows the burned gases to escape. The device is especially useful in apparatus with catalytic burners.

United States Patent [72] Inventor Roger Risse 3,072,468 1/1963 Stitzer 431/12 X Caluire, France 3,295,585 1/1967 Kovach, Jr. et al. 431/22 X [21] App1.No. 802,600 3,307,613 3/1967 Rexer 431/76 [22] Filed Feb. 26, 1969 3,321,001 5/1967 Vezzoli... 431/22 [45] Patented Oct. 5,1971 3,354,931 11/1967 Risse 431/76 X [73] Assignee Societe Lyonnaise Des Applications c t l fi u FOREIGN PATENTS Caluire (Rhone), France 613,136 11/1960 Italy 431/76 Pnomy 2: 53 1968 Primary ExaminerFrederick L. Matteson [3 l 1 49499 Assistant Examiner-Robert A. Dua

Attorney-Waters, Roditi, Schwartz & Nissen [5,4] APPARATUS ABSTRACT: A safety device for gas apparatus has a pilot flame at the base of a tube with a thermocouple close beside [52] US. Cl 31/76, the flame, Spaced above the flame is a metal grill not reached 23/23 /2 431122 by the flame when it burns in an atmosphere of normal com- [51 l lnt. position. when the air has a (K)2 content the flame i dis.

of Search l [76, 75, placed from the pilot nozzle and is to {he The her. 2 23/232 mocouple therefore cools and actuates the closure of the gas supply to the apparatus. A gridded aperture in the base allows [56] References air to flow in past the thermocouple thereby aiding its cooling. UNITED STATES PATENTS A gridded aperture at the top of the tube allows the burned 2,166,104 7/1939 Collbohm 73/25 UX gases to escape. The device is especially useful in apparatus 2,818,246 12/1957 Kappel 73/25 X with catalytic burners.

SAFETY DEVICE FOR GAS APPARATUS The present invention relates to a safety device for gas apparatus.

Safety devices having recourse to a pilot flame and fitted to apparatus functioning by gas have hitherto relied on one of the following three operational principles: flame extinction, angular deformation of the flame, and flame lengthening.

In applying one the of these three principles, operation is established as follows:

When the ambient air has a normal content of oxygen the pilot flame contacts the sensitive element of a thennocouple; the latter is then brought to a sufiicient temperature to deliver an electric current which, transmitted to an electromagnetic valve, enables the latter to be held in open position, which has the result of feeding normally with gas the apparatus that it is desired to control.

On the other hand, if the ambient atmosphere is impoverished in oxygen, which in practice is manifested by an increase in the level of C0, in the three cases above (extinction, deformation or flame lengthening), the said flame no longer contacts the sensitive element of the thermocouple sufficiently; the latter then cools and the electric current that it delivers is not strong enough so that the electromagnetic valve closes, which results in the controlled apparatus no longer being supplied with gas.

Previous safety devices operating on these principles are subject to drawbacks such as untimely cut off by the electromagnetic valve through a momentary mass of foul air; slow cooling of the 'thermosensitive element and hence slow response of the cutoff system; accumulation of unburned bypass gas in flame extinction devices and vulnerability of the flame to external disturbances.

It is an object of the present invention'to provide an improved safety device which overcomes one or more of the above-mentioned drawbacks.

It is another object of the present invention to provide a new method of operation of a safety device based on the displacement of a pilot flame, as distinct from extinction, deformation or elongation of a flame.

' According to the invention there is provided a safety device for gas apparatus having gas supply closure means, said device comprising a combustion chamber for a pilot flame, gas bypass means including a burner tip for supplying said pilot flame, said burner tip being located in a lower part of said combustion chamber, a thermosensitive element connected to said closure means and arranged laterally in immediate proximity to said burner tip so that it is exposed to the pilot flame, flame-retaining means arranged at a distance from the burner tip such that it is not reached by the flame when the latter burns in an atmosphere of normal composition, although when the atmosphere is vitiated, and in particular its C0, level increases, the flame is displaced by being detached from the burner tip and is caught on the flame retaining means so that it is spaced from the thermosensitive element which is thus less subject to radiation and, on cooling, actuates said closure means.

The safety device comprises a metastable pilot flame which can be located at the base of a tube, with a sensing element such as a thermocouple situated laterally in immediate proximity to the burner of said bypass so that it is contacted by the flame, is surmounted by a flame-retention means situated at a distance such that it is not reached by the said flame when the latter burns in an atmosphere of normal composition, while when the atmosphere is vitiated, and in particular if its C0, level increases, this flame is displaced by separating from the tip of the burner and by being positioned on the aforesaid flame retention means so that it is spaced from the sensitive element of the thermocouple which is thus less subjected to radiation and, in cooling, actuates the closure of the supply of the apparatus.

The above-mentioned obstacle can be constituted by a-' crosspiece or any other suitable mechanical embodiment.

Due to the aforesaid conception, said tube is not of solid metal but is at least partly composed of a grill closing all the openings, of the same nature as a minerslamp which apparatus, as is conventionally known antideflagrating.

The addition of this device to a heating apparatus therefore confers additional qualities of safety, especially when it relates to an apparatus operating by catalysis, that is to say without a flame.

Numerous additional advantages result from this safety device; and include the following; The pilot flame, enclosed in a tube, becomes insensitive to the influence of air currents.

in the case of a momentary mass of foul air, the flame separates and is displaced to become positioned on the flame retentionmeans but returns immediately to the burner tip as the mass has passed; since the flame is not extinguished there is therefore no untimely cut off by the electromagnetic valve in the case of a transient mass of foul air.

When the ambient air is vitiated by an abnormal level of C0,and the flame is caught on the flame retention means its radiation does not influence the sensitive element of the thermocouple sufficiently, the latter cools quickly and this all the more since it is exposed to a flow of cold gas which flows between the tip of the bypass and the flame retention means the response of the system is therefore rapid.

During this response period the gas of the bypass continues to burn, which eliminates the risk and the danger of flame extinction systems: The flame is inaccessible, which constitutes an additional advantage from the safety point of view.

lt is to be noted, moreover, that in the detection position (flame detached and caught on the flame retention means the shut-off actuated by the thermocouple cannot cause the total cut off of the gas supplying the apparatus, but simply reduces its flow rate to a value corresponding to idling operation off the apparatus. If one asumes that the ambient air returns to normal, the flame will thus take up its original position and, at this moment, the head of the thermocouple being reheated restores to the apparatus its full gas flow.

in this latter case of nonnal operation, it is not possible to use an electromagnetic valve which necessitates being fed to put it in open" position but a bulb thermostat is perfectly suitable and enables the production of an assembly operation as a regulator, the apparatus being put into idling condition as soon as the ambient air has reached the C0 level for which the safety device has been regulated.

At this moment, the production of CO being lowest and the atmosphere again becoming normal the safety system is restored to the position of nominal working. This operation may be repeated indefinitely. I

In order that the invention may be more fully understood an embodiment of the safety device according to the invention is described below solely by way of illustrative example and with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 represents one embodiment of the safety the position of normal operation;

FIG. 2 shows the embodiment of HO. 1 in detection position and FIG. 3 illustrates the scheme of an installation using an embodiment of a safety device according to the invention, operating as a regulator on a catalytic heating apparatus.

Referring to the drawings, metallic tube 1 closed at the bottom la and top lb to define a combustion chamber comprises an air-intake grill 2 and into which tube 1 is placed the nozzle 3 of a metastable bypass flame 4. Laterally, in' immediate proximity to this nozzle 3, is placed a sensitive thermocouple element 5.

Above the flame 4 is placed a grill 6 which serves as a flame retention means and normally, is not reached by the said flame, and which grill 6 includes two rods 60 and 66 extending transversely of one another. At the upper part of the tube 1, above the grill 6, are provided orifices 7 or a grill for the evacuation of the burned gases.

This tube comprises, obviously .a side gate (not shown enabling the lighting of the bypass flame.

device in FIG. 1 shows the position occupied by the flame when it is fed by ambient air of normal composition of oxygen; the grill 6 is not reached by this flame and he sensitive elementis periodically contacted by it, hence is heated and actuates the opening valve of the gas feeding the apparatus.

If the composition of ambient air is no longer normal, the flame takes up the position of FIG. 2, that is to say, separates from the nozzle 3 and comes to be caught above the grill 6. The sensitive element 5 is no longer subject to the same flame radiation; it cools and causes total or partial closing of the supply of gas to the apparatus. If the composition of the ambient air returns to normal, the flame will return to its original position and the thermocouplereheated to provide full gas flow. The flame retention means 6 thus must be so constructed that the passages therethrough are of adequate cross section to enable the flame 4 to return to the burner tip 3 when the composition of the ambient air returns to normal. FIG. 3 shows the case of a regulator lay-out, that is to say with only partial closure.

ln this figure the thermosensitive element 5 is constituted by a bulb with capillary tube 8 controlling a thermostat 9 governing a valve 10 to which the gas is conducted from a bottle 11 with reducing valve 12 and stop cock 13 through a conduit 14.

This valve comprises two outlets l5 and 16 connected to a common conduit 17 and comprising two nozzles 18 and 19 of different diameters nozzle 18 corresponding to a gas flow for normal supply to a catalytic gauze 20, while nozzle 19 only enables a supply for idling operation of this gauze. On the conduit 17 is connected the supply 21 to the nozzle 3 of the bypass.

it will be apparent that various changes and modifications may be made in the embodiments described without departing from the essential concept of the invention as defined in scope by the appended claims.

I claim:

1. A safety device for gas apparatus having gas supply closure means, said device comprising means defining a combustion chamber for a pilot flame, gas bypass means including a burner tip for supplying gaseous fuel for said pilot flame,

said burner tip being located in a lower part of said combustion chamber, a thennosensitive element connected to said closure means and arranged to laterally extend into said combustion chamber in immediate proximity of said burner tip so that it is exposed to the pilot flame, flameretaining means arranged in said combustion chamber and spaced above the burner tip such that it is free from contact by the flame when the latter burns in an atmosphere of normal composition, said flame-retaining means being spaced proximate said flame and remote from said thermosensitive element such that when the CO level of the atmosphere increases, the flame is displaced by being detached from the burner tip to be caught on the flame-retaining means within the combustion chamber so that is spaced remote from the thermosensitive element which is thus subjected to reduced radiation so as to undergo cooling and actuate said closure means, said flame-retaining means being constructed so that the passages therethrough are of adequate cross section to enable said pilot flame to return to the burner tip when an atmosphere of nonnal composition resumes.

2. A safety device according to claim 1, wherein the flameretaining means is a grill.

3. A safety device according to claim 1, wherein said combustion chamber is in the form of a tube.

4. A safety device according to claim 1, wherein said combustion chamber has openings to the atmosphere which are grilled.

5. A safety device according to claim 1, wherein the thermosensitive element is a bulb thermostat.

6. A safety device according to claim 1, wherein gridded openings are provided in said combustion chamber.

7. A safety device according to claim 1, wherein an opening in said chamber to the atmosphere is provided on each side of the grill, one said opening bein located in an up r part of the chamber to provide an outlet or burned gas an another said opening being located in the lower part of the chamber to enable air to flow into the chamber and pass over the thermosensitive element whereby it cools moore rapidly when the flame is displaced from the burner tip.

8. A catalytic heating apparatus including as a regulator a safety device as claimed in claim 1. 

1. A safety device for gas apparatus having gas supply closure means, said device comprising means defining a combustion chamber for a pilot flame, gas bypass means including a burner tip for supplying gaseous fuel for said pilot flame, said burner tip being located in a lower part of said combustion chamber, a thermosensitive element connected tO said closure means and arranged to laterally extend into said combustion chamber in immediate proximity of said burner tip so that it is exposed to the pilot flame, flame-retaining means arranged in said combustion chamber and spaced above the burner tip such that it is free from contact by the flame when the latter burns in an atmosphere of normal composition, said flame-retaining means being spaced proximate said flame and remote from said thermosensitive element such that when the CO2 level of the atmosphere increases, the flame is displaced by being detached from the burner tip to be caught on the flame-retaining means within the combustion chamber so that is spaced remote from the thermosensitive element which is thus subjected to reduced radiation so as to undergo cooling and actuate said closure means, said flame-retaining means being constructed so that the passages therethrough are of adequate cross section to enable said pilot flame to return to the burner tip when an atmosphere of normal composition resumes.
 2. A safety device according to claim 1, wherein the flame-retaining means is a grill.
 3. A safety device according to claim 1, wherein said combustion chamber is in the form of a tube.
 4. A safety device according to claim 1, wherein said combustion chamber has openings to the atmosphere which are grilled.
 5. A safety device according to claim 1, wherein the thermosensitive element is a bulb thermostat.
 6. A safety device according to claim 1, wherein gridded openings are provided in said combustion chamber.
 7. A safety device according to claim 1, wherein an opening in said chamber to the atmosphere is provided on each side of the grill, one said opening being located in an upper part of the chamber to provide an outlet for burned gas and another said opening being located in the lower part of the chamber to enable air to flow into the chamber and pass over the thermosensitive element whereby it cools moore rapidly when the flame is displaced from the burner tip.
 8. A catalytic heating apparatus including as a regulator a safety device as claimed in claim
 1. 